Perfluoroelastomers (elastomeric perfluoropolymers) are polymeric materials which exhibit outstanding high temperature tolerance and chemical resistance. Consequently, such compositions arc particularly adapted for use as seals and gaskets in systems in which elevated temperatures and/or corrosive chemicals are encountered. The outstanding properties of perfluoropolymers are largely attributable to the stability and inertness of the copolymerized perfluorinated monomer units which make up the major portion of the polymer backbone, e.g., tetrafluoroethylene and perfluoro(alkyl vinyl) ethers. In order to achieve good elastomeric properties, the perfluoropolymers must be crosslinked. To this end, a small percentage of cure site monomer is copolymerized with the perfluorinated monomer units. Cure site monomers containing nitrile groups, such as perfluoro-8-cyano-5-methyl-3,6-dioxa-1-octene, are especially preferred. Such compositions are described in U.S. Pat. Nos. 4,281,092 and 4,394,489; and in International Application WO 95/22575.
Curing of nitrile-containing perfluoroelastomers may be effected by treatment with organometallic compounds such as tetraphenyltin. However, organotin cures of these compositions have been found to be slow. It would be highly desirable to develop a nitrile-containing perfluoroclastomer composition which cures rapidly and which, when cured, maintains the excellent thermal stability and chemical resistance that is characteristic of perfluoroelastomers. U.S. Pat. No. 5,447,993 discloses a method of rapidly curing nitrile-containing perfluoroelastomers through use of a dual cure system containing both an organotin compound and an organoperoxide. However, methods for enhancing cure rate when organometallic curing agents are used in the absence of peroxides have not heretofore been known.